The present invention relates to a single-leaf valve for gas-fired boilers and, more specifically, to a valve for a boiler that comprises a combustion chamber in which pulsewise combustion involving a fuel and an oxidant occurs, the fuel/oxidant mixture being introduced into this chamber in an intermittent manner.
Several devices for supplying a pulsed-combustion chamber with a fuel/oxidant mixture are described in French Patent Application No. 84 04 921 which, dated Apr. 29, 1984, was filed in the name of the Applicant. In each of the devices thus described, the oxidant, in this instance air, is introduced into the combustion chamber through inclined orifices that are provided in an upper plate, whereas the fuel, for example heating oil, is continuously injected by means of a spray nozzle or injection head which is screwed into a bore that is provided in the upper plate.
In one embodiment, a valve leaf is installed between the inside face of the upper plate and a valve leaf seat which is fixed to the throat of the combustion chamber.
In another embodiment, a plurality of valve leaves are installed in a manner such that they possess translational mobility inside centering stops which are fixed to the upper plate. In all cases, the leaf (or leaves) is (or are) pressed flat against the upper plate when, following the initial explosion, the pressure in the combustion chamber becomes higher than the pressure at which the air is injected.
For this reason, when the boiler is not operating, and/or when low pressures prevail in the combustion chamber, the valve leaf (or leaves) is (or are) open, and air is introduced into the pulsed-combustion chamber. Moreover, and because of the very construction of the valve leaves and upper plate, it is difficult to reduce the leaf opening time during operation. In fact, the application of one plane surface to another, namely the pressing of the valve leaves flat against the facing surface of the upper plate, necessitates a higher pressure at the moment when the air is admitted to the pulsed-combustion chamber.
Lastly, it should be noted that it is rather difficult to produce a fuel/oxidant mixture.